1. Field of the Invention
The present invention relates to a computer program product, system, and method for injecting congestion in a link between adaptors in a network.
2. Description of the Related Art
In a Storage Area Network, congestion occurs as a consequence of a slow draining adaptor in the network, which causes delays and congestion in a link between the slow draining adaptor and a linked adaptor. Fibre Channel adaptors are assigned credits indicating a number of frames an adaptor may transmit to a linked port. Upon sending a frame to the linked port, credits are decremented. Upon receiving a reply from the receiving port indicating the frame was processed, credits are incremented. Sending or receiving frames is halted for the duration that the respective buffer credit is zero. During the period of zero buffer credit, the adaptor enters error path handling mode. Proper handling of errors such as time outs, lost frames, alternate path selection, etc. is critical for the successful operation of the adaptor. Debugging and providing fixes once the product is in field is much more expensive than catching these problems during the development cycle. For these reasons, developers may want to force congestion among the links in a network to test how the adaptors and components handle errors.
To introduce congestion in the network during development, hardware devices referred to as jammers may be connected to the network and simulate dropped frames or congested links. Additional components may be provided to overload the target ports and test error handling at the ports.